Aircraft are commonly equipped with cabin outflow valves, which are modulated during flight to maintain cabin air pressure within a desired range. The cabin outflow valve can include, for example, a frame, a first door (e.g., a first rectangular butterfly plate) pivotally mounted to a first portion of the frame, and a second door (e.g., a second rectangular butterfly plate) pivotally mounted to a second portion of the frame. The outflow valve may be mounted in the aircraft fuselage such that the first door is closer to the tail of the aircraft than is the second door; for this reason, the first door and the second door may be referred to as the “aft door” and the “forward door,” respectively. The aft and forward doors may be mechanically linked by one or more linkages and move in unison between a closed position and a partially open or “cruise” position. In the cruise position, the partially opened doors permit pressurized air to flow from the aircraft fuselage to the ambient environment to reduce fuselage pressure and, perhaps, to provide additional thrust to the aircraft. In the closed position, the doors sealingly engage one another and the inner periphery of the frame to deter the outflow of pressurized air from the aircraft fuselage.
Modern cabin outflow valves can achieve relatively low leakage levels when in a closed position and subject to pressure loading during flight. Nonetheless, there exists a continued demand to provide cabin outflow valves having further reduced leakage levels. This presents a significant technical challenge as conventional approaches utilized to reduce outflow valve leakage are now largely exhausted or associated with certain undesirable tradeoffs. For example, previous approaches in reducing outflow valve leakage commonly focused on increasing conformity between the sealing surfaces of the outflow valve. However, manufacturing tolerances render further improvements in sealing surface conformity generally impractical without a substantial increase in manufacturing costs. Another manner in which outflow valve leakage can be reduced is through stiffening the outflow valve doors by adding material thereto. Stiffening the valve doors in this manner, however, increases manufacturing cost and adds undesired weight to the outflow valve. Finally, a cabin outflow valve can be produced to include various reinforcement structures, which serve to apply a more uniform closing force to the valve doors and thereby reduce leakage; however, this again adds undesired weight, bulk, and manufacturing cost to the outflow valve.
An ongoing need thus exists for a cabin outflow valve providing exceptionally low leakage levels when in a closed position and subject to pressure loading during flight. Ideally, embodiments of such a cabin outflow valve could be produced without adding weight, bulk, or significant manufacturing cost to the outflow valve. It is also desirable to provide embodiments of cabin pressure control system including such an ultralow leakage cabin outflow valve. Lastly, and more generally, it is desirable to provide embodiments of a laterally-sealing valve, which offers one or more of the foregoing benefits regardless of whether the valve is specifically implemented as a cabin outflow valve. Other desirable features and characteristics of the present invention will become apparent from the subsequent Detailed Description and the appended Claims, taken in conjunction with the accompanying Drawings and the foregoing Background.